Sully Island

Island · Salt water · in The Severn Estuary

A tidal island off the Glamorgan shore joined to the mainland by a shingle and rock causeway that covers on every tide. Rough ground and reef off the seaward side, which is what holds the fish and what costs the tackle.

Safety: tides and being cut off — can cause serious injury or death. 2 more points apply here.

What each one does, and what reduces it ↓

FishingHQ describes what this place is, not whether you may fish it. Access, permits and who to ask.

What you can catch here

Documented at this place, grouped by how you would be fishing, with how strongly the sources support each one. This is what has been written down, not a forecast, and being listed is never permission to fish.

From the shore · 8

What these strengths mean

Established quarry: Fishing sources describe this as a normal local target here, not merely as caught.
Seasonal: Well supported, and concentrated in part of the year rather than spread through it.
Recorded here: At least one credible public account of this species being caught here. That is all it means.
Places, accounts and sources are counted separately: A fish documented once at each of six marks is still documented once at each of six marks. Breadth is reported as a place count and never raises the strength, and sources are deduplicated across places so one publisher covering a whole coast counts as one. A fishery account is a source describing the fishing; a recorded catch is a report of a specific catch. They are counted apart because they are not the same evidence.

How people fish it

Practised here: Sea fishing.

Methods the sources name for this ground. Each one is explained in full on its own page.

Ledgering
Fishing a bait on the bottom held by a weight, with no float — the simplest way to fish at distance, in depth, or in wind.
Surfcasting
Casting heavy baited tackle from a beach into surf — a method defined by distance, by tide, and by reading water that all looks the same.
Spinning
Casting an artificial lure and retrieving it so that it moves like something alive — the most direct form of lure fishing.

The ground and the water

The ground: A tidal island off the Glamorgan shore joined to the mainland by a shingle and rock causeway that covers on every tide. Rough ground and reef off the seaward side, which is what holds the fish and what costs the tackle.
Exposure: Open south into the Bristol Channel, with the island itself the only shelter there is.
Depth: Shallow over the causeway, deepening quickly off the seaward rock.
Tide and flow: The causeway floods on every tide and the crossing is the whole risk of the mark. People are cut off here regularly.

Through the year

Cod and whiting through the winter; bass and rays over the rough ground in the warmer half.

The months the sources attach to each species here. Where a species carries no season it is listed underneath rather than assumed to run through the year.

The months in which each profiled species is recorded as quarry at this location.
Species	J	F	M	A	M	J	J	A	S	O	N	D
European sea bass — established quarry, recorded in May, June, July, August, September, October.
Atlantic cod — seasonal, recorded in November, December, January, February.
Whiting — seasonal, recorded in November, December, January, February.

Recorded here with no season stated: Conger eel, Thornback ray, Blonde ray, Bull huss, Small-spotted catshark.

Safety

Tides and being cut off — Can cause serious injury or death

The flood fills the ground behind an angler before it covers the ground in front, so the water arrives between them and the shore while the position they are standing on is still dry.

What reduces it: Read the tide table before going rather than after arriving, set a leaving time from the tide rather than from the fishing, and identify the exit and how long it takes while the ground is still uncovered.

Cold water shock — Can cause serious injury or death

UK coastal and inland water is cold enough for most of the year to trigger the involuntary gasp and the loss of swimming ability that decides most immersion deaths, and it does so within the first minute, long before hypothermia is relevant.

What reduces it: Wear a buoyancy aid rather than carry one, carry a means of calling for help on the person rather than in a bag, and plan on the assumption that an unplanned entry into the water is survivable only if somebody knows immediately.

Moving water and currents — Can cause serious injury or death

Tidal streams here are among the strongest around Britain and are unsurvivable to swim against. Underwater visibility is effectively nil, so anybody in the water cannot see and cannot easily be seen. Soft mud can trap a person, and being stuck in mud on a rising tide in this estuary is a recognised recurring emergency.

What reduces it: Stay off soft mud entirely, fish from hard ground, wear a buoyancy aid where there is any chance of going in, and if trapped in mud call for help immediately rather than after struggling. Do not enter the water for any reason.

Rules and access

FishingHQ does not know the current access position here. Shore angling in Wales is not rod-licensed, but access rights, landowner permission, local authority and harbour byelaws, national and inshore fisheries measures, and site designations all apply and all change. Check the current position with Natural Resources Wales, the harbour or local authority, and the landowner before going.

Who holds the answer:

Natural Resources Wales, which administers marine and fisheries regulation in Welsh waters.
The local authority and, where one exists, the harbour authority, for access, byelaws and shellfish classification.
The environment agency in England and natural resources Wales, for migratory salmonids, eels, elvers and the historic net and fixed-engine fisheries.
The inshore fisheries and conservation authority for the English side, and the Welsh government's marine and fisheries function on the Welsh side, for sea fishing.
The statutory nature conservation bodies, for the European habitat and bird designations and the site of special scientific interest covering the estuary.
The harbour authority for the port and navigation areas, whose rules govern access to piers, walls and navigable channels.
The local authority and food standards agency, for shellfish ground classification and biotoxin monitoring.

Nearby fishing

Other publicly documented places within about 40 km, by distance. Positions are approximate public geography and are never exact marks.

Lavernock Point — 2–5 km · Headland
Barry Island and Nells Point — 2–5 km · Headland
Penarth Pier — 5–10 km · Pier
The Cardiff foreshore — 5–10 km · Estuary mark
Aberthaw — 10–25 km · Beach section
Sand Point — 10–25 km · Headland
Brean Down — 10–25 km · Headland
Weston-super-Mare — 10–25 km · Beach

Sully Island and the publicly documented places around it. Approximate positions, not marks. Positions are approximate by design — they are capped at about a hundred metres and describe where a named public place is, not where fish are and not a mark. Everything plotted here is also listed below.

Sources for this place

Sea Angler — Bauer Media (Specialist angling publication)Relied on for: Long-running published description of British sea angling practice by region, ground type and named mark.FishingHQ's interpretation of what it saysCitation checked — the work exists and is described correctly
General angling website restatements of established technique — Various (Credible secondary source)Relied on for: Widely restated public descriptions of which places are conventionally fished and how, recorded as practitioner consensus rather than as scholarship, and not relied on for access, permission or any current rule.Background and mechanism onlyCitation checked — the work exists and is described correctly
British Sea Fishing: Welsh shore marks — British Sea Fishing (Credible secondary source)Relied on for: Mark-by-mark Welsh shore angling: which species are fished for at each named mark, in which season, and with which baits and methods.States this directlyPassage read and verified
Fishing in Wales — sea fishing marks and location guides — Angling Trust (Angling or fisheries organisation)Relied on for: Welsh sea fishing marks: the ground, the species targeted at each, the mode, the state of tide and the weather preconditions, as set out by the national angling body's own Welsh resource.States this directlyPassage read and verified

How FishingHQ labels evidence is explained in the evidence policy. Last reviewed 2026-08-16.

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